Power transistors are transistors which provide for large current and voltage amplitudes and are thus suitable for directly operating loads with relatively large powers. Power transistors are used, for example, in output stages and switching stages for industrial electronics and motor vehicle engineering.
In this context, the temperature of a power transistor represents a significant factor for its functional capability. An overtemperature of the power transistor, generated, for example, by a higher ambient temperature or by malfunction such as a short circuit of loads, can lead to it being damaged or destroyed and in addition can also lead to impairment or even destruction of the load. It is essential, therefore, to detect any overtemperature of power transistors in time and reliably in order to be able to take suitable measures such as, for example, switching off the transistor or the load before critical temperature values and thus the damage limit are/is reached.
To determine the temperature of a semiconductor component, a temperature sensor can be attached to the package of the semiconductor component or to its semiconductor body/chip. It can be inappropriate that the sensor and the actual semiconductor component are two separate components, as a result of which the sensor only detects the temperature externally on the semiconductor component which can deviate considerably from the temperature in the interior of the semiconductor component and, in addition, has an unwanted inertia in the case of rapid temperature changes in the interior of the semiconductor component. It is precisely the temperature in the interior of the semiconductor body, however, which is relevant to the determination of critical operating states.
There is a general need for a circuit arrangement with a temperature sensor which is integrated into the same semiconductor body like the power transistor, where the temperature sensor reliably provides a voltage dependent on the temperature in the interior of the semiconductor body.